Belt grinding machine



Nov. 3,` 1959 K. HEESEMANN BELT GRINDING MACHINE Filed April 19, 1957 '7 Sheets-Sheet 1 NVE/vra@ K Heesemann Nav. 3, 1 959 K. HEESEMANN 2,910,809

BELT GRINDING MACHINE Filed April 19, 1957 7 sheets-sheet 2 Heesemarm Nov. 3, 1959 K. HEESEMANN 2,910,809

BELT GRINDING MACHINE Filed April 19, 1957 fr sheets-sheet s [C Heesemann n gygy* g* da Nov. 3, 1959 K. HEESEMANN BELT GRINDING MACHINE '7 Sheets-Sheet -4 Filed April 19, 1957 K.. Heemarz Nov. 3, 1959 K. HEESEMANN 2,910,809

BELT GRINDING MACHINE Filed April 19, 1957 7 Shee'os--Sheetl 5 wwf/vra@ K. HeeSemo/ Nov. 3, 1959 K. HEEsEMANN 2,910,809

BELT GRINDING MACHINE:

Filed April 19. 1957 7 Sheets-Shet 6 F7C-i6 C l14T/C5. 7 zii' Q IL G wrm/raf? K Hee senz/c1171? By l Nov. 3, 1959 K. HEEsr-:MANN

BELT GRxNDxNG MACHINE 7 Sheets-Sheet 7 Filed April 19, 1957 /NVENOP KjHeesemam ATTYS.

United States Patent C) BELT GRINDlNG MACHINE Karl Heesemann, Rehme, via Bad Oeynhausen, Germany Application April 19, 1957, Serial No. 654,011

Claims priority, application Germany April 28, 1956 15 Claims. (Cl. 51--141) This invention relates to grinding machines, and more specifically to an automatic grinding machine with an endless circulating abrasive belt which is led around two spaced belt pulleys and pressed by pressure means against a workpiece fed preferably perpendicularly to the longitudinal axis of the abrasive belt.

The object of the invention is to improve the known grinding machines in that the abrasive belt is pressed in a uniform manner against the workpiece to be ground and, in particular, is guided in such a manner that it is continually in contact with the entire length of the workpiece or any desired fraction thereof, without thereby overloading the abrasive belt and preventing the removal of dust.

A further object of the invention is to provide a grinding machine in which even the thinnest veneers may be evenly ground without cutting through the top laminatio-n.

Still another object of the invention is to provide a grinding machine in which the effective grinding length of the belt may be easily and exactly controlled, this being absolutely vital in certain types of fine sanding operations. i

A further object of the invention is to provide a grinding machinewhich is capable of long life and which is resistive to the heavy wear which commonly occurs when the pressure means is applied to the abrasive belt.

Still another object of the invention is to provide an improved machine which is sturdy and economical to build and maintain.

Several preferred embodiments of the invention are illustrated by way of example in the accompanying drawings, in which:

Fig. 1 is a front elevation of an automatic belt grinding machine with circulating pressure members;

Fig. 2 is a top plan view of the automatic belt grinding machine shown in Fig. 1, with a portion taken in section and as provided with an additional sanding belt with a reciprocable pressure member for rough grinding;

Fig. 3 is a vertical cross section through the machine illustrated in Fig. 2;

Fig. 4 is a diagrammatic front elevation of a modified belt grinding machine with circulating pressure band;

Fig. 5 is a top plan view thereof with a portion taken in section;

Fig. 6 is a cross section through the same machine taken on line VI-VI of Fig. 5;

Fig. 7 is a side elevational View of a pressure band with V-shaped pressure strips;

Fig. 8 is an enlarged top plan view of the outer side of this pressure band;

Fig. 9 isa side elevational view of a modified detail of the beltgrinding machine;

Fig. 10 is a vertical cross section thereof taken on line X-X of Fig. 9, and

Fig. 1l is a top plan view thereof.

`of l to 3 meters per second.

ice

Similar reference numerals refer to similar parts throughout the several figures.

Referring now to the drawings, Figs. l to 3 show automatic belt grinding machines on uprights 10 and 11. Bracket members are secured to these uprights 10 and 11 and carry gui-de rods 12 on which a main supporting table 14 for carrying a workpiece 15 to be ground is arranged horizontally shiftable by means of rollers 13.

The uprights 10 and 11 carry belt pulleys 16 and 17 around which an endless abrasive belt 18, provided with an abrasive on its outer side, circulates in the direction of the arrow at a speed of, for example, 25 meters per second. For this purpose the belt pulley 16 is driven in the direction of the arrow by a motor 19.

A supporting beam 20 is fixed on the uprights 10, 11 at the height of the belt pulleys 16, 17 driven by the motor 19, and carries adjacent one of its ends a motor 21 which drives a pair of sprocket wheelsl 22. Another pair of sprocket wheels 23 is provided at the other end of the machine. Two endless chains 24 and 25 run over the pairs of sprocket wheels 22 and 23 and carry ten frames 26. Instead of chains, ropes, belts or any other suitable means may be used. These frames 26 have laterally projecting frame parts 27 which slide in longitudinal grooves provided in stationary bars 28. To a portion 29 of each frame 26 one end of an angle piece 30 is pivoted, the free end of which is acted upon by a torsion spring 31 which is also carried by the frame portion 29. A pressure member 33 consisting of a pressure plate is pivoted on the middle of the angle piece 30. The free end of the angle piece carries a roller 35 which bears, under the action o-f its torsion spring 31, against the underside of pressure rails 36, 37, 38. These pressure rails 36, 37, 38 are arranged one behind the other in longitudinal direction and the rails 36 and 38 are bevelled at their ends adjacent the pairs of sprocket wheels 22, 23 to allow the rollers 35 to run on and ol. The length of the pressure rails corresponds to the distance between the centers of neighboring individual pressure members, with the result that as a ,roller runs off the pressure rail, the next following roller runs onto it at the same time. Each of the pressure rails 36, 37, 38 is mounted on an elbow lever 39 hinged to an upright 40 mounted on the supporting beam 20. A rod 42 is linked at one end to the piston rod of a pressure cylinder 43, as at 41, and at its other end to the elbow lever 39.

The pressure members 33 press against the inner side of the abrasive belt 18 circulating between the belt pulleys 16, 17, the abrasive belt being provided with abrasive material on its outer side and moving on the workpiece 15 transversely to the direction of feed thereof.

A narrow sanding belt 44 driven by one of belt pulleys 45, 46, around which it is led, may be arranged in front of the abrasive belt 18, as shown in Figs. 2 and 3. A pressure member 47 is shiftable on a guide rail 48 between the upper and lower guide paths of this sanding belt 44 in the longitudinal direction thereof. This pressure member 47V can be moved to and fro by hand, being at the same time pressed against the inner side of the sanding belt 44. The sanding belt 44 can therefore rough-grind veneers which are provided with joint paper or have particularly rough places. The veneers are then finely ground automatically in a single operation by the abrasive belt 18 with the circulating pressure members.

The circulating chains 24, 25 provided with the pressure members 33 have, for example, a circulating speed Instead of the endless chains 24, 25, ropes, belts, endless bands of strip steel, felt, rubber or suitable plastic materials to which the individual pressure members are attached so that they are movable or fixed as desired, may also be employed.

Instead of the individual pressure rails 36, 37, 38 for each pressure cylinder 43, an elastic pressure beam can also be used which, due to its elasticity, produces such compensation that the grinding pressure of all pres'zure members 33 is equally great. The individual pressure members 33 can also be replaced by a plurality of small pressure strips which are arranged preferably transversely, that is at right angles or oblquely to the longitudinal direction of the chains, ropes or bands.

The modified form of construction illustratedA in Figs. 4' to l-l has within the abrasive belt 18 a belt pulley 51 driven by a motor 50 in the direction of the arrow and a freely rotating belt pulley 52, on which pulleys an endless circulating pressure band 53 runs.

The pressure band 53 (Figs. 7 and 8)- consists of a exible foundation 54 of thin strip steel which preferably has the same width as the abrasive belt 18. lt may, however, also be made from textile fabric or a plastic or similar material suitable for this purpose. On the outer side of this foundation 54 thin laminated pressure strips 55 of V-shape are stuck at equal distances apart. These strips 55 have surfaces which are formed, for example, of fine glass beads and thus have a low frictional coeflicient and great resistance to wear. These pressure strips S5 are substantially rigid in themselves, that means they are inelastic in the direction of pressure; they are preferably 5 to 2O mms. in width and can be of different thicknesses. Even a thickness of 0.5 to l mm. is suicient to meet requirements. Owing to the slight thickness of the laminated pressure strips 55 the whole pressure band 53 is of such light weight that it runs just as smoothly as the abrasive belt 18. The speed of the pressure band 53 amounts to, for example 3 to 5 meters per second. It runs at a constant yet slower speed than the abrasive belt 18 and in the same direction as this belt.

For the grinding operation an elastic pressure beam 56 acts on the inner side of the lower guide path of this pressure band 53 and can be moved perpendicularly to the grinding plane by a piston or other device 5S through the intermediary of levers 57. ln its lower position this pressure beam 56 presses the pressure band, with the V-shaped pressure strips pointing in the direction of travel, against the abrasive belt l. This pressure acts against the inner side of the abrasive belt so that this slides with its outer side stripwise over the workpiece to be ground. Owing to spaces 59 left between the laminated pressure strips 55, the abrasive belt 1S cornes only partly into contact with the surface to be ground. The dust caused by the grinding is thus led olf laterally so that a tine grind of surprisingly fine quality can be attained. In the case of a wide grinding width a relatively low frictional resistance occurs` with the result that the pressure band 53 is subjected to relatively little tensional stress. Therefore, means for guiding the pressure band 53 can be dispensed with because the intrinsic tension of the pressure band 53 is sucient to ensure good running during the grinding operation.

If, instead of laminated pressure strips 55, larger and thicker pressure strips are arranged on the foundation 54 serving as traction and guide band, it may then be advisable to guide the pressure band, for example, from the sides.

The pressure strips, particularly the laminated pressure strips,may also be of curved or corrugated shape; however, they may also be replaced by a sin-gle pressure strip `which is xed in zig-zag or serpentine form on the foundation 54 in the longitudinal direction thereof.

The elastic pressure beam 56 can be made in one piece in order to attain an absolutely uniform pressure on the individual pressure strips 55 of the pressure band 53, so'that there are no joints. To obtain good elasticity, an intermediate layer of foamed or expanded rubber is preferably arranged on the pressure beam 56. The actual grinding length can be determined by an underlayer of felt or similar material which can be arranged under the pressure beam so that its position can be changed.

As shown in Figs. 9 to 1l, the elastic pressure beam 56 may preferably consist of a rigid support 60 to the underside of which an elastic pressure element 61 is xed. This pressure element 61 may consist of soft or foamed rubber or of a tube of rubber or plastic which is lilled with liquid or the like. A plate 62 of exible steel, such as spring steel or material possessing similar properties, is located under the pressure element 61, particularly in the case of a tube-like construction, in order to form a good supporting Surface. For the purpose of controlling the elasticity of the tubular pressure element 61, the quantity of liquid can be regulated by a regulating valve 63. In this connection a supplementary container 64 is preferably connected with the regulating valve 63 and has, for example, a pump piston 65, so that the liquid can be drawn off or recharged as required.

For adjusting the length of grinding a mat 66 of yieldable material, particularly felt or the like, is located between the pressure element 61 or the steel plate 62 and the circulating pressure band 53 and held at both ends x and y by strips of fabric 67, for example twill. These strips of fabric 67 can be wound onto and olf rollers 68 in the direction of the arrows, so that, for example the point x can be displaced in the longitudinal direction of the pressure element 61 and with it the effective grinding surface can be changed in area perpendicularly to the direction in which the workpiece to be ground is fed.

From the above detailed description of the invention, it is believed that the construction will at once be apparent, and while there are herein shown and described preferred embodiments of the invention, it is nevertheless to be understood that minor changes may be made therein without departing from the spirit and scope of the invention as claimed.

I claim:

1. In an automatic grinding machine, a frame, a pair of spaced pulleys rotatably supported on said frame, an endless abrasive belt rotatable on said pulleys, drive means for at least one of said pulleys, a work supporting table positioned below and adjacent said abrasive belt, means for moving said table and the work supported thereon in a direction transversely of the direction of movement of said endless abrasive belt, pressure means positioned within said abrasive belt and adjustable substantially perpendicularly to the direction of movement of said belt and acting on the inner side thereof to press said belt against the work being fed through said machine on said table, and a mat of yieldable materialdisposed for movement to a selected portion thereof into position between said pressure means and said abrasive belt, whereby the placing of one end of said mat in said selected position between the ends of the pressure means by said movement will define the effective grinding length of the belt, said mat including free ends, a thin strip of flexible material secured to said free ends, and reeling and unreeling means secured to strips for positioning said mat in a selected position between the ends of said pressure means.

2. An automatic grinding machine as set forth in claim l, wherein the mat consists of felt.

3. An automatic grinding machine as set forth in claim l, wherein the yieldable mat is supported by the pressure means.

4. An automatic grinding machine as set forth in claim 1 wherein the pressure means includes an elongated supporting bar and a resilient pressure element between the bar and the mat.

5. An automatic grinding machine as set forth in claim 1 wherein the pressure means includes an elongated supporting bar, a resilient pressure element supported thereon and asteel plate interposed between said pressureelement and said mat.

6. An automatic grinding machine as set forth in claim l, wherein the pressure means includes an elongated Supporting bal. anda lipid inflatable tlexible envelope nordsee supported by said bar and positioned between said bar and said mat.

7. The structure of claim 6 in which a pressure band is interposed between the flexible envelope and the endless abrasive belt, said pressure band is operative to press the abrasive belt against work to be ground and is in direct contact with the longitudinally adjustable mat.

8. An automatic grinding machine as set forth in claim 1, wherein an endless pressure band is supported on spaced drive pulleys and moves between said mat and said abrasive belt.

9. The structure of claim 8 in which said pressure band comprises a thin metal band including narrow pressure strips formed on the surface thereof engaging said abrasive belt, said strips extending obliquely to the longitudinal direction of travel of said abrasive belt.

10. The structure of claim 9 in which said pressure band and pressure strips are formed as a laminated construction.

11. The structure of claim 8 in which said pressure band comprises a textile fabric band including narrow pressure strips formed on the surface thereof engaging said abrasive belt, said strips extending obliquely to the longitudinal direction of travel of said abrasive belt.

12. An automatic grinding machine as set forth in claim 1, wherein an endless pressure band is supported on spaced drive pulleys and moves between said mat and said abrasive belt, said pressure band further having relatively thin, spaced, V-shaped pressure strips formed on the surface thereof with the points of said strips extending in the direction of travel of the pressure band.

13. An automatic grinding machine as set forth in claim 1 in which said strip of exible material comprises a strip of fabric.

14. An automatic grinding machine as set forth in claim 1 in which said reeling and unreeling means is supported by said pressure means.

15. An automatic grinding machine as set forth in claim 1 in which said mat comprises a layer of substantially resilient rubber-like material extending along the eective grinding length and backed by a rigid support.

References Cited in the file of this patent UNITED STATES PATENTS 295,535 Coy Apr. 8, 1884 685,328 Gale Oct. 29, 1901 743,608 Yarnell Nov. 10, 1903 799,694 Tyden Sept. 19, 1905 818,518 Clemons Apr. 24, 1906 1,043,194 Blevney Nov. 5, 1912 2,633,679 Cross et al. Apr. 7, 1953 

